Hi,

I've just tried the new 3.7 beta 38 for windows (which is the first beta release
I've tried).

My problem is that when I try to render the rad_def_test.pov, I only get a black
image, and I can't figure out why.

I'm sure it's just some settings I haven't thought about but I don't know what.

If someone can give me some help about that, it would be very useful.

Thanks in advance !

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Am 01.09.2010 16:55, schrieb Darats:
> Hi,
>
> I've just tried the new 3.7 beta 38 for windows (which is the first beta release
> I've tried).
>
> My problem is that when I try to render the rad_def_test.pov, I only get a black
> image, and I can't figure out why.

POV-Ray 3.7 complements the "ambient" finish parameter with another one, 
"emission", to distinguish between some added brightness for fake 
ambient illumination (classic "ambient" keyword), and genuine object 
glow (new "emission" finish keyword).

The fake ambient illumination is now automatically turned off when 
radiosity is used, as that's exactly what radiosity is designed to 
compute more realistically. (Think of "ambient_light" automatically 
being forced to zero.) As a consequence, the "ambient" mechanism can no 
longer be used to model light sources in radiosity-only scenes.

Enter emission. This new mechanism does virtually the same as "ambient", 
except that it is unaffected by the global "ambient_light" parameter, 
and is active in both classic and radiosity scenes.


There are two simple solutions to fix existing scenes:

(A) Replace the "ambient" keyword with "emission" wherever it is used to 
model a light source.

(B) Alternatively, place a "#version 3.6" statement in the scene. 
POV-Ray will then revert to a backward-compatibity mode, leaving the 
"ambient" mechanism active in radiosity scenes.


> I'm sure it's just some settings I haven't thought about but I don't know what.

Nothing wrong on your side. The sample scenes just haven't been updated 
yet to match the new mechanism.

Post a reply to this message

clipka <ano### [at] anonymousorg> wrote:
> Am 01.09.2010 16:55, schrieb Darats:
> > Hi,
> >
> > I've just tried the new 3.7 beta 38 for windows (which is the first beta release
> > I've tried).
> >
> > My problem is that when I try to render the rad_def_test.pov, I only get a black
> > image, and I can't figure out why.
>
> POV-Ray 3.7 complements the "ambient" finish parameter with another one,
> "emission", to distinguish between some added brightness for fake
> ambient illumination (classic "ambient" keyword), and genuine object
> glow (new "emission" finish keyword).
>
> The fake ambient illumination is now automatically turned off when
> radiosity is used, as that's exactly what radiosity is designed to
> compute more realistically. (Think of "ambient_light" automatically
> being forced to zero.) As a consequence, the "ambient" mechanism can no
> longer be used to model light sources in radiosity-only scenes.
>
> Enter emission. This new mechanism does virtually the same as "ambient",
> except that it is unaffected by the global "ambient_light" parameter,
> and is active in both classic and radiosity scenes.
>
>
> There are two simple solutions to fix existing scenes:
>
> (A) Replace the "ambient" keyword with "emission" wherever it is used to
> model a light source.
>
> (B) Alternatively, place a "#version 3.6" statement in the scene.
> POV-Ray will then revert to a backward-compatibity mode, leaving the
> "ambient" mechanism active in radiosity scenes.
>
>
> > I'm sure it's just some settings I haven't thought about but I don't know what.
>
> Nothing wrong on your side. The sample scenes just haven't been updated
> yet to match the new mechanism.

All right, I did the #version 3.6 trick and it worked perfectly.

Now, the probleme is that I can't get exactely the same result as the 3.6
version. Here my colors seem to be "washed out" (it's like everything is more
"grey" and less shiny than on the 3.6 version). I don't know what to do.

Any guess on that ?

Post a reply to this message

On 09/02/2010 08:42 AM, Darats wrote:
> clipka <ano### [at] anonymousorg> wrote:
>> Am 01.09.2010 16:55, schrieb Darats:
>>> Hi,
>>>
>>> I've just tried the new 3.7 beta 38 for windows (which is the first beta release
>>> I've tried).
>>>
>>> My problem is that when I try to render the rad_def_test.pov, I only get a black
>>> image, and I can't figure out why.
>>
>> POV-Ray 3.7 complements the "ambient" finish parameter with another one,
>> "emission", to distinguish between some added brightness for fake
>> ambient illumination (classic "ambient" keyword), and genuine object
>> glow (new "emission" finish keyword).
>>
>> The fake ambient illumination is now automatically turned off when
>> radiosity is used, as that's exactly what radiosity is designed to
>> compute more realistically. (Think of "ambient_light" automatically
>> being forced to zero.) As a consequence, the "ambient" mechanism can no
>> longer be used to model light sources in radiosity-only scenes.
>>
>> Enter emission. This new mechanism does virtually the same as "ambient",
>> except that it is unaffected by the global "ambient_light" parameter,
>> and is active in both classic and radiosity scenes.
>>
>>
>> There are two simple solutions to fix existing scenes:
>>
>> (A) Replace the "ambient" keyword with "emission" wherever it is used to
>> model a light source.
>>
>> (B) Alternatively, place a "#version 3.6" statement in the scene.
>> POV-Ray will then revert to a backward-compatibity mode, leaving the
>> "ambient" mechanism active in radiosity scenes.
>>
>>
>>> I'm sure it's just some settings I haven't thought about but I don't know what.
>>
>> Nothing wrong on your side. The sample scenes just haven't been updated
>> yet to match the new mechanism.
> 
> All right, I did the #version 3.6 trick and it worked perfectly.
> 
> Now, the probleme is that I can't get exactely the same result as the 3.6
> version. Here my colors seem to be "washed out" (it's like everything is more
> "grey" and less shiny than on the 3.6 version). I don't know what to do.
> 
> Any guess on that ?
> 
> 
most likely one or all or a combination of the following ....
assumed_gamma, display_gamma, file_gamma. you should probably acquaint
yourself with the changes associated with the changes in the
revision.txt file or have a look at:
http://wiki.povray.org/content/Documentation:Tutorial_Section_1#Changes_and_New_Features_Summary
particular attention to item number 7 under the "Look Here First" heading

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Am 02.09.2010 13:42, schrieb Darats:

> Now, the probleme is that I can't get exactely the same result as the 3.6
> version. Here my colors seem to be "washed out" (it's like everything is more
> "grey" and less shiny than on the 3.6 version). I don't know what to do.
>
> Any guess on that ?

Gamma.


This is the typical effect of gamma correction, which POV-Ray 3.6 didn't 
do properly (with the result that scenes were designed "wrong" to /look/ 
"right"), but which POV-Ray 3.7 now does a pretty good job at (with the 
result that scenes designed "wrong" now indeed /look/ "wrong".)


Now the first thing to note here is that theoretically, POV-Ray 3.7 
/should/ do gamma correction in the same "wrong" way as 3.6 when 
"#version 3.6" is used. What you observe is that this doesn't seem to be 
the case, so we /may/ still have an issue there, and I'll have a closer 
look at this.

I might need a bit of information for this purpose:

- What is the Display_Gamma setting you use (if any)?
- What is the File_Gamma setting (if any)?
- Are you using "assumed_gamma" in the scene? If so, what is it set to?
- Are you using image-based textures in the scene?

You might need to have a look at the master POVRAY.INI for this purpose. 
Note that POV-Ray 3.6 and 3.7 have separate master POVRAY.INIs.

Post a reply to this message

clipka <ano### [at] anonymousorg> wrote:
> Am 02.09.2010 13:42, schrieb Darats:
>
> > Now, the probleme is that I can't get exactely the same result as the 3.6
> > version. Here my colors seem to be "washed out" (it's like everything is more
> > "grey" and less shiny than on the 3.6 version). I don't know what to do.
> >
> > Any guess on that ?
>
> Gamma.

Ok, I've tried to play with the gamma setting before, but with no results.
>
>
> This is the typical effect of gamma correction, which POV-Ray 3.6 didn't
> do properly (with the result that scenes were designed "wrong" to /look/
> "right"), but which POV-Ray 3.7 now does a pretty good job at (with the
> result that scenes designed "wrong" now indeed /look/ "wrong".)
>
>
> Now the first thing to note here is that theoretically, POV-Ray 3.7
> /should/ do gamma correction in the same "wrong" way as 3.6 when
> "#version 3.6" is used. What you observe is that this doesn't seem to be
> the case, so we /may/ still have an issue there, and I'll have a closer
> look at this.
>
> I might need a bit of information for this purpose:
>
> - What is the Display_Gamma setting you use (if any)?

So, I haven't set any Display gamma anywhere (3.6 or 3.7) so it should be
default values for both versions.

> - What is the File_Gamma setting (if any)?

No file gamma too.

> - Are you using "assumed_gamma" in the scene? If so, what is it set to?

I use an assumed gamma of 1.2 on my 3.6 scene, so the same value in 3.7 is much
darker, if I add #version 3.6 it is much better but the colors look more "grey"
as I explained before.

> - Are you using image-based textures in the scene?

No it is just colored materials for the objects but I have a HDR image as a
sky_sphere





>
> You might need to have a look at the master POVRAY.INI for this purpose.
> Note that POV-Ray 3.6 and 3.7 have separate master POVRAY.INIs.

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Am 04.09.2010 01:50, schrieb Darats:

>> - Are you using "assumed_gamma" in the scene? If so, what is it set to?
>
> I use an assumed gamma of 1.2 on my 3.6 scene, so the same value in 3.7 is much
> darker, if I add #version 3.6 it is much better but the colors look more "grey"
> as I explained before.

Ah, yes, we have a problem here:

With POV-Ray 3.7, only the assumed_gamma values of 1.0 or 2.2 work as 
previously, even when a #version 3.6 statement is present.


Try using "assumed_gamma 1.0" in the scene, and setting the 
"Display_Gamma" and "File_Gamma" INI file options to 1.8333 (=2.2/1.2); 
I'm not perfectly sure, but I /think/ this might do the trick. Make sure 
to /not/ use PNG, HDR or EXR as output file format though, as those are 
too smart file formats and won't be fooled by this kind of hack.


>> - Are you using image-based textures in the scene?
>
> No it is just colored materials for the objects but I have a HDR image as a
> sky_sphere

HDR images are "gamma-safe", you can't do anything wrong there.

Post a reply to this message

clipka <ano### [at] anonymousorg> wrote:
> Am 04.09.2010 01:50, schrieb Darats:
>
> >> - Are you using "assumed_gamma" in the scene? If so, what is it set to?
> >
> > I use an assumed gamma of 1.2 on my 3.6 scene, so the same value in 3.7 is much
> > darker, if I add #version 3.6 it is much better but the colors look more "grey"
> > as I explained before.
>
> Ah, yes, we have a problem here:
>
> With POV-Ray 3.7, only the assumed_gamma values of 1.0 or 2.2 work as
> previously, even when a #version 3.6 statement is present.
>
>
> Try using "assumed_gamma 1.0" in the scene, and setting the
> "Display_Gamma" and "File_Gamma" INI file options to 1.8333 (=2.2/1.2);
> I'm not perfectly sure, but I /think/ this might do the trick. Make sure
> to /not/ use PNG, HDR or EXR as output file format though, as those are
> too smart file formats and won't be fooled by this kind of hack.
>

Perfect, now I have the same results as 3.6 but with the ulti-threading of 3.7.

Thanks a lot for your help !

>
> >> - Are you using image-based textures in the scene?
> >
> > No it is just colored materials for the objects but I have a HDR image as a
> > sky_sphere
>
> HDR images are "gamma-safe", you can't do anything wrong there.

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